Fig 1.

Multiphase CTA and follow-up MR imaging of an 83-year-old woman presenting with acute right upper limb weakness and dysphasia. A, Axial MIP of the first phase demonstrates subtle paucity of vessels in the distribution of the left MCA compared with the right side. B, Axial MIP of the second phase demonstrates the delayed vessel sign (long arrow). There is delayed enhancement of the distal left MCA via pial collateral vessels (short arrows). This vessel is not seen on the first phase due to the presence of an M2 vessel occlusion. C, Axial MIP of the third phase also demonstrates the “delayed” left MCA vessel (long arrow). D, DWI b=1000 image 2 weeks postpresentation demonstrates a recent infarct (arrow) in the same left MCA territory.